Aboy speaks one language at home and another at school. The white kids want to know where he is from. The answer is “here”, same as them, but that’s not what they’re asking. After 9/11 they call him Osama. His parents are from Pakistan. When he visits Karachi, his relatives point out his US accent. He lives between two worlds, belonging to neither.

Then, in the sixth grade, something happens. He is doing a science project on Isaac Newton. He visits the public library of the small town in Pennsylvania where he lives, and, browsing books about Newton the scientist he comes across another Newton – Huey P Newton, cofounder of the Black Panther Party. In 1973, Newton published an autobiography called Revolutionary Suicide. Intrigued by the title, the boy picks up the book, and it changes his life.

This is the scene that opens Mistaken Identity: Race and Class in the Age of Trump. It’s vividly drawn, and sets the stakes for what follows. Asad Haider has written a book about identity, politics, and the relationship between the two. In particular, he has written a book about “identity politics”, a phrase that, like “political correctness”, is extremely slippery, but which generally means an emphasis on issues of racial, gender and sexual identity.

Identity politics finds critics everywhere. Throw a rock at a rack of newspapers and you’ll probably hit an editorial condemning it. Conservatives such as Republican House speaker Paul Ryan blame it for polarisation, while liberals like the Columbia University historian Mark Lilla hold it responsible for Donald Trump’s victory, applying the baroque logic that letting people use their preferred gender pronouns is why Democrats struggle to be seen as the party of working people.

Haider is also a critic of identity politics, but with a crucial difference: he knows the history of the term and is working from within the tradition that produced it. As he explains, the idea has radical roots. It originated with the Combahee River Collective, an organisation of black lesbian feminist socialists in Boston who published a landmark statement in 1977: “This focusing upon our own oppression is embodied in the concept of identity politics. We believe that the most profound and potentially most radical politics come directly out of our own identity, as opposed to working to end somebody else’s oppression.”

This is the original demand of identity politics, and it’s one that Haider embraces: for a revolutionary practice rooted in people’s identities as racialised, sexed, gendered and classed individuals who face interlocking systems of oppression. These systems have to be fought together, by organising people of different identities in what Haider calls “a project of universal emancipation” devoted to dismantling all of the structures that make them unfree, including and especially capitalism itself.

But if anticapitalist revolution is where identity politics began, it has since become something quite different, and is now invoked by certain liberals and leftists to serve distinctly non-revolutionary ends, Haider argues. It involves members of marginalised groups demanding inclusion, recognition, or restitution from above – a seat at the table. These demands are made in response to very real injuries endured by those groups. But their method, he says, ends up strengthening the structures that produced those injuries in the first place.

Drawing on Wendy Brown’s idea of “wounded attachments”, Haider contends that identity politics causes people to become invested in their marginalisation as a source of identity, and to continuously enact that identity as a form of politics. This approach can extract occasional concessions from the system but cannot build the power necessary to transform it.

Building that power will require forging a “new insurgent universality”, Haider believes. This doesn’t mean pretending that everyone is the same. It doesn’t mean elevating one identity – that of the white male worker, say – above all others. Rather, the universality that Haider wants is built from below. It is “created and recreated in the act of insurgency”, as people come together to combat the common enemy lurking behind their particular oppressions. Freedom for ourselves – whoever “we” are – is inseparable from freedom for everyone. If emancipation is always self-emancipation, self-emancipation is always a collective endeavour.

Collective self-emancipation doesn’t require abandoning one’s identity – if that were even possible – but linking it with those of others in widening circles of solidarity. The story that opens Haider’s book is a good example: solidarity across identities is how a Pakistani-American boy could find inspiration in a long-dead Black Panther. Indeed, what Haider found so inspiring about Newton was precisely his vision of a solidarity strong enough to span the world. As an African American in a profoundly racist country, Newton couldn’t escape his identity. Neither could Haider, in a country convulsing with Islamophobic hatred. Yet “Newton did not stop with his own identity”, Haider writes. “His experience led him beyond himself – to take up a politics based on solidarity with Cuba, China, Palestine and Vietnam.”

Armed with the explanatory power of the black radical tradition, and Marxism more broadly, Newton connected the dots between different injustices. Haider follows this example, wielding the same tools to advance his critique of contemporary identity politics and make his case for a radical alternative. He draws on a wide range of sources, examining an interracial uprising in colonial Virginia and the riots in Newark three centuries later; exploring the ideas of WEB Du Bois, Judith Butler and Barbara Fields, among other great thinkers. And he regularly loops back to recent history, to analyse Occupy Wall Street, Black Lives Matter and the other mobilisations that have moulded our political moment.

The result is riveting. Haider moves deftly over difficult terrain. His prose is precise and propulsive. His Marxism is not a mausoleum but a living, breathing thing, coursing with what Lenin called “the concrete analysis of the concrete situation”, faithful to the method of historical materialism while flexible in the face of a fluid social reality. And he writes as both a militant and a theorist, one who believes that theory is integral to political struggle and that theoretical rigour has political stakes.

The function of rigorousness, Louis Althusser once said, is to distinguish between “true ideas and false ideas”, between ideas that “serve the people” and ideas that serve its enemies. The American left has shown signs of life recently, but it has no shortage of enemies. Defeating them will require, among other things, ideas. Haider’s book contributes several. We will need more.

• Mistaken Identity: Race and Class in the Age of Trump is published by Verso. To order a copy for £9.34 (RRP £10.99) go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.